Answer:
13.
Explanation:
we will use the distance formula. I have also provided a picture in an online graphing calculator if you ever want to use that. I can't provide a link, but just look up "Desmos" and you'll find it.
(13-1)^2+(8-3)^2
12^2+5^2
144+25
169
√169 = 13
Have a wonderful day! :-)